
Here \(n\in \mathbb {Z}\)  is the unit cell index. \(\sigma _{x,y,z}\)  are
Pauli matrices acting on the two sublattices in each unit cell. \(J_{1,2}\) 
and \(i\lambda \)  describe symmetric and asymmetric parts of intercell
hopping amplitudes. \(\mu \)  is the intracell coupling strength. The
Floquet operator \(U=e^{-i\frac{1}{2}H_{1}}e^{-i\frac{1}{2}H_{2}}\) 
that governs the evolution of the system over a driving period (e.g.,
from \(t=0\)  to 1) is nonunitary once \(\lambda \ne 0\) , yielding
a model that could possess non-Hermitian FTI phases,
which are characterized integer or half-integer quantized topological invariants
under the periodic boundary condition (PBC) [1]}.
Under the open boundary condition (OBC), the CS of the model \(\Gamma ={\mathbb {I}}_N\otimes \sigma _{z}\) 
(\(N\)  is the number of unit cells and \({\mathbb {I}}_N\)  is an \(N\times N\)  identity)
allows multiple edge modes to appear in pairs at the quasienergies
zero and \(\pi \) , whose numbers can be determined by the bulk winding
numbers \(\nu _{0}\)  and \(\nu _{\pi }\)  (see Appendix  for their definitions).
These edge modes are further found to coexist with sufficient amounts
of bulk states localized around the edges of the system due to the NHSE [1]}.
